Gunsmithing .018” Throat Wear

[SporterII]

How much indicates “toast”?
1500 rds. Fired. .018 base to ojive measured increase. Still hitting steel at distance.

 

[Edds]

If that is that an .018" increase from a new unfired chamber, it is nothing. Krieger says the throat length can increase .005"- .030" during break in.

 

[FCS]

How much indicates “toast”?
1500 rds. Fired. .018 base to ojive measured increase. Still hitting steel at distance.

Barrel is "toast" when stops giving you desired / needed accuracy at max distance you'll be shooting rifle.
When you start getting uncalled fliers at an increasing rate, barrel is giving you warning it is going to quit sooner than later.
What cartridge are you shooting?

 

[SporterII]

243
H4831
3030

 

[MakeSawdust]

That is nothing for that combo. I run a 243ai with h1000 in Criterion barrels and typically get around .004-.005" of throat movement per 100 rounds.

 

[Steel head]

My 7 saum has twice that and still hammers steel.

 

[Doc68]

My 6 creed barrel went quicker than that. I was pushing 95gr Sierra TMK at about 3250 and burnt my barrel at about 1900 rds. Wouldn't hold MOA after that.

Used h4350
Peterson brass
Cci LRP
Ruger precision.

Now its rebarreled to 7mm-08 AI.

 

[SporterII]

My barrel burning 243 was the victim of fake news I guess.

 

[FCS]

Every bbl is different.
What is your accuracy requirement?
Usually somewhere in 1400 rd range, start getting increased fliers at increasing rate.
Run barrel hot like would happen in PRS match or practicing for PRS rate of fire? That’s harder on a barrel then keeping barrel a little cooler.

Barrels are consumables, don’t get too attached.
When barrel stops giving needed accuracy, spin on another and don’t look back.

 

[SporterII]

I saved it. It can spin right back on.
Good replies, TNX

 

[jrbet83]

My Smith and I tracked multiple barrels for two years. Mine, my buddies, and some of his other clients. Guy's would bring their guns in from time to time for him to measure bc his shop is about 500yds from our club matches. He kept a log. From 6BRs, to 6.5 Creedmoors and lots in between ( 6 Creed, Dashers, 6SLR, his XC) they all averaged between .003" to .006" per hundred rounds. I've seen a lot of cases where folks on this forum have said, "my barrel has 1400rds on it and it's only eroded .002"...". I think it's a lot more common that folks have subjective or unrepeatable measuring techniques. And using a different lot bullet than what they started with is a big culprit. I've seen different lots of 105 Hybrids measure .006" from base to ogive and the resulting OAL measurement in the barrel will be as much as .015".

But, how much erosion? All the answers above about velocity and accuracy loss are what I would agree with, but to also give context my barrels usually go with about .090" to .120" on them.

I would agree 100%. And your data mimics almost exactly what’s been documented time and time again in other posts. The BR variants stay around the .003-.005 per 100 range and the bigger case capacity 6’s stay in the .005-.007 range. I actually just did a ton of research/forum reading on the subject trying to decide which route I wanted to go with my next 6mm.

 

[MakeSawdust]

I find that managing carbon and fire cracking in the throat will make a barrel go a long time. I avg. 2500 rds on the above barrels. I scrub the carbon in the throat with JB every 200-400 rds. The barrels slow down as the throat erodes, but can be brought back by chasing lands and adding powder. They shoot under 3/4 minute to 800 yds or I dump them. Usually that is within 200 rds of 2500 one way or the other.

As I get more into this, I think I am going to stop shooting them at matches at either 2000 or 2200 rds. I'm almost to the point where I have a barrel that is broken in and ready to go when the one I have been shooting gets to a high round count.